Heat-dissipating shield



Feb. 27-, 1962 D. K. ALLISON HEAT-DISSIPATING SHIELD I Filed May 18, 1959 INVENTOR. flow/41.0 K/zusm/ 4 f L%zara z 6 United States Patent Q 3,023,264 HEAT-DISSIPATING SHIELD Donald K. Allison, Albuquerque, N. Mex, assignor to Cool Fin Electronics Corporation, Los Angeles, Calnh, a corporation of Nevada Filed May 18, 1959, Ser. No. 814,091

16 Claims. (Cl. 17435) My invention relates to electronic devices, and more particularly to heat-dissipating shields for vacuum tubes, transistors, diodes, rectifiers, etc. My invention also rehates to electrostatic and magnetic shielding elements for use with such'components. l

The so-called tube shields of contemporary practice have been designed primarily for shielding of the electron tube elements from electrostatic fields and thereby to prevent the resultant feed-back, oscillation, interference, and noise. These shields ordinarily take the form of cylinders, partially closed at one end, and inverted over the vacuum tube. While such devices serve to shield the tube from external electrostatic fields with some degree of effectiveness, it has been found that these shields reflect and retain the heat generated by operation of the tube within the tube envelope, greatly increasing the operating temperatures within the tube and seriously decreasing tube life and operating reliability. Efforts hat e been made to overcome these problems by providing the tube shield with a liner element which physically contacts a portion of the area of the tube envelope and conducts the heat therefrom to the shield, from which it is dissipated by radiation and conduction. However, these liner-type devices suffer from several defects in their basic principles. In the first place, the liner element contacts only a portion of the hot area of the tube envelope, and therefore is only partially effective in removing the heat from the envelope. Furthermore, localized temperature gradients lead tostrains and cracks in the envelope with consequent destruction of the tube. Also, these shield liner elements create regions or pockets of stagnant air which impede the transfer of heat from the tube envelope to the outer shield from whence it can be dissipated. In other words, most contemporary tube shields are designed in an inside-out manner, and do not efficiently perform the required function of absorbing and dissipating the heat from the tube elements and envelope in the most eflicient manner.

It is an object of my invention to provide heat-dissipating shields which intimately contact substantially all of the hot area of the envelope of the vacuum tube or device, and which provide efficient means to dissipate the heat from the internal elements andenvelope by absorption, radiation, and conduction.

It is a further object of my invention to provide vacuum tube enclosures which efifectively shield the tube elements from ambient electrostatic and/ or electromagnetic fields.

It is an additional object of my invention to provide heat-dissipating shield structures which are readily adaptable to a wide range of sizes and shapes of vacuum tube, transistor, and semiconductor devices.

A further object of my invention is to provide tube shield structures in which the tube can be removed and replaced without disturbing the attachment of the shield to the chassis or heat-sink.

An additional object of my invention is to provide heat-dissipating tube shields which physically occupy no more total volume and cross-sectional area than the shields now in use, and yet which provide an increased heat-dissipating area of higher efiiciency than that obtainable in contemporary tube shields;

.It is a still further object of my invention to provide various forms of heat-dissipating tube shields which perform the above functions and in addition serve to mechanically protect and support the vacuum tube or other component, and to retain it firmly in the tube socket or component position under conditions of mechanical shock or vibration.

These and other objects and advantages of my invention will be apparent to persons skilled in the art from consideration of the following exemplary description of several embodiments of the invention. Referring to the drawings: p

FIGURE 1 depicts a preferred form or" my invention,

which is particularly well adapted to use with the common glass-envelope miniature tubes;

FIGURE 2 is a cross-sectional view through A--A of FIGURE 1;

FIGURE 3 shows the shield structure of FIGURE 1 in the opened position for tube changing;

FIGURE 4 illustrates a modified form of my invention which consists of separate elements designed to be bonded directly to the tube envelope;

FIGURE 5 shows one of the elements of FIGURE 4;

FIGURE 6 is a view of an alternate form of my in' vention;

FIGURE 7 is a magnified partial sectional view showing the construction of the body of the shield structure of FIGURE 6;

FIGURE 8 depicts an additional alternative form of my invention; and

FIGURE 9 is a magnified partial vertical sectional view of the structure of FIGURE 8.

Referring now to FIGURE 1, a vacuum tube 1 is enclosed and shielded by a substantially continuous cylinder formed by L-section members 2, 2, 2", etc., and filler members 3, 3, 3", etc; the cooperation of the alternating rib members and filler members to form the cylindrical shield being shown more clearly in sectional view FIG- URE 2. The L-section rib elements 2, 2', 2", etc., are preferably formed from a flat sheet by punching and bending; the lower ends of these elements terminating in a continuous band of sheet material integral therewith which is wrapped around during the cylinder-forming operation to produce the tubular section 50 for mating with existing tube sockets, and which may be flanged to provide fastening means for securing the shield structure to a chassis or heat-sink. The filler elements 3, 3', etc., are similarly formed by stamping from a flat sheet, and terminates in a continuous band of sheet material intergal therewith which is rolled in tubular formduring the cylinder-forming operation and is concentrically bonded to the tubular section 50 during assembly. The rib elements 2, 2', 2", etc., and the filler elements 3, 3, 3", etc. are interleaved and shaped in the assembly operation in such manner as to produce a substantially continuous cylinder of such radius as to effectively contact the cylindrically curved surface of the vacuum tube, as is clearly shown in FIGURE 2. As may be seen in FIGURES 1 and 3, the upper ends of the rib elements 2, 2, 2", etc., and the filler elements 3, 3, 3", etc., are curled over to form a series of guide loops of which loops'4 and 5 are exemplary. A lock wire 6 passes through the series of guide loops 4 and 5 and has one of its ends attached to the anchor pivot 8 of a toggle-lock 7, and its other end attached to the swinging end of the toggle-lock. Thus, when the toggle-lock 7 is in the closed position, the lock-wire 6 draws the upper ends of the rib elements and the filler elements into the closed position, thereby maintaining the rib elements and the tiller elements in intimate contact with the surface of the tube envelope and securely holding the vacuum tube in the tube socket, as shown in FIGURE 1. When the 3 toggle-lock 7 is swung to the open position shown in FIGURE 3, the lock-wire 6 is loosened, thereby permitting the rib elements 2, 2, 2", etc., and the filler elements 3, 3, 3", etc., to separate and curve outwards, making the vacuum tube 1 readily accessible for removal.

Heat removed from the tube envelope by conduction and by absorption of radiant energy is dissipated from the tube shield by radiation from the tins and cylindrical surface of the shield, and by conductive heat transfer to the air in contact with the shield. Heat also is conducted from the tube envelope through the shield to the chassis or heat-sink 9, from whence it is dissipated by radiation and conduction.

Referring now to FIGURE 4, which depicts an alternative structure for the shield. of FIGURE 1, a vacuum tube 11 is provided with heat radiating and conducting fins 12, 12, 12", etc., which serve to effectively shield the vacuum tube elements from ambient electrostatic and electromagnetic fields, and to provide efficient cooling of the tube envelope. The fin elements 12, 12, 12", etc., are bonded to the tube envelope by means of a suitable bonding material (such as epoxy resin), thereby providing physical support for the fin elements and effective thermal conductive contact between the tube envelope and the fin elements. As may be seen in FIGURES 4 and 5, the lower end of each of the fin elements terminates in a curved tab; the combination of the tabs from all of the fin elements forms a resilient cylindrical structure which provides thermal and electrical conductive contact with an annular ring 13 which is in intimate contact with an electronic chassis or heat sink 14, and which provides a thermal conductive path for enhanced dissipation of heat from the vacuum tube 11. The extent of the curved portion of each of the shield elements 312, 12', 12,", etc., and the length of these elements, can be readily adapted to provide heat-dissipating structures and shield elements for a wide range of vacuum tube envelope diameters and lengths, as well as to provide heat-dissipating shield elements for transistors, diodes, rectifiers, and other semiconductor devices. Furthermore, the fin elements can be so shaped as to conform to tube envelopes of irregular contour, making it possible for the first time to provide heat-dissipating shields for components of this type.

In the form of my invention shown in FIGURES 6 and 7, a vacuum tube 21 is enclosed by a ribbed helicalcoil shield 25. The lower end of the shield 25 is attached to a flanged ring 27, which in turn is intimately attached to a chassis or heat-sink 26, thereby providing effective conduction of heat from the shield to the heatsink. As is shown in FIGURE 7, the shield 25 consists of a helical coil formed from sheet metal which has been shaped by forming-rolls to provide a heat-dissipating rib 24 and which also includes an offset overlap 23 to provide substantially continuous physical contact of the shield 25 with the heated region of the tube envelope 21, and, in cooperation with the removable shield cap 22, to provide uninterrupted electrical shielding of the vacuum tube elements. The helical-coil shield element 25 is formed to a diameter slightly less than that of the vacuum tube 21. Unwinding the helix provides sufficient increase in diameter of the shield to permit insertion and removal of the tube from the shield, and the spring action of the helical coil causes the shield to firmly contact the tube envelope when the tube is in position in the shield, thereby providing e'lfective conductive heat transfer from the tube envelope to the shield and holding the vacuum tube securely in the tube socket. The fin 24 formed by the outwardly-turned portion of the helical coil provides effective surface for radiation and conduction of heat to the air in contact with the tube shield. The helical coil structure which forms the shield can be singleor multipleelernent construction; i.e., it can be formed of one helical strip, or from two or more cooperative helical strips interlaced to generate the cylindrical shield as shown in FIG- URE 7.

In the form of my invention illustrated in FIGURES 8 and 9, a vacuum tube 41 is enclosed by a shield 42 which is provided with heat dissipating fins 43, 43', 43", etc. The cylindrical body of the shield 42 is slit lengthwise at 46 to permit accommodation of slight variations in the diameter of the tube envelopes of vacuum tube 41. As shown in FIGURE 8, the shield element 42 is provided with a skirt 44 which terminates in a flange for attachment and heat conduction to a chassis or heatsink 45.

Having described and illustrated my invention and its modifications, I do not wish to be limited to the particular forms shown herein, except as covered by my appended claims.

I claim:

1. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous metallic envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially con tinuous good heat conducting contact therewith, and forming a shield against ambient electrical fields, said shield having a socket engaging portion thereon providing for low resistance thermal and electrical contact to an electronic chassis; and heat dissipating elements attached to said metallic envelope and extending outwardly therefrom to augment the heat dissipating surface area of the shield.

2. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous metallic envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially continuous good heat conducting contact therewith, and forming a shield against ambient electrical fields, said shield having a socket engaging portion thereon providing for low resistance thermal and electrical contact to an electronic chassis; heat dissipating elements attached to said metallic envelope and extending outwardly therefrom to augment its heat dissipating surface area, said metallic shield envelope and said non-metallic component envelope being readily separable by removal of one from the other so that the shield may cooperate with other components as desired.

3. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous sheet metal envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially continuous good heat conducting contact therewith, and forming a shield against ambient electrical fields, said shield having a socket engaging portion thereon providing for low resistance thermal and electrical contact to an electronic chassis; and heat dissipating elements integrally attached to said sheet metal envelope and extending outwardly therefrom to augment the heat dissipating surface area of the shield.

4. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous sheet metal envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially continuous good heat conducting relation therewith, and forming a shield against ambient electrical fields; and heat dissipating elements integrally attached to said sheet metal envelope and extending outwardly therefrom to augment its heat disipating surface area, said sheet metal envelope being formed of substantially discrete elements which combine about the envelope of the electronic component to form a substantially continuous electrical shield.

5. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous sheet metal envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially continuous good heat conducting contact therewith, and forming a shield against ambient electrical fields, said sheet metal envelope including substantially discrete elements, at least some of which have substantially curved portions engaging the component envelope, and fins integral with said curved portions and extending outwardly therefrom to augment the heat dissipating surface area of the shield.

6. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous sheet metal envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially continuous good heat conducting contact therewith, and forming a shield against ambient electrical fields, said sheet metal envelope including substantially discrete elements, at least some of which have substantially curved portions engaging the component envelope, and fins integral with said curved portions and extending outwardly therefrom to augment the heat dissipating surface area of the shield; and means for holding said discrete elements in good thermal contact with the component envelope.

7. A heat dissipating, electrical shield for electronic components comprising: a sheet metal envelope formed to closely embrace the non-metallic envelope of an electronic component in good heat conducting contact therewith, and forming a shield against ambient electrical fields, said sheet metal envelope including substantially discrete elements at least some of which have substantially curved portions engaging the component envelope, and fins integral with said curved portions and extending outwardly therefrom to augment the heat dissipating surface area of the shield; and a plastic cement bonding said discrete elements to the component envelope in relatively good heat conducting relation therewith.

8. A heat dissipating, electrical shield for electronic components comprising: a sheet metal envelope formed to closely embrace the non-metallic envelope of an electronic component in good heat conducting contact therewith, and forming a shield against ambient electrical fields,

said sheet metal envelope including substantially discrete elements at least some of which have substantially curved portionsengaging the component envelope, and fins integral with said curved portions and extending outwardly therefrom to augment the heat dissipating surface area of the shield; and a relatively good heat conducting cement affixing said curved portions to the component envelope in relatively good heat conducting relation therewith.

9. A heat dissipating, electrical shield for electronic components as defined in claim 1 in which the shield envelope is formed from a spiral strip having a portion defining a surface extending parallel to the axis of the spiral and adapted to engage the surface of the component envelope in good thermal contact therewith, said spiral strip having a second portion integrally attached to said first portion and extending angularly therefrom to augment the heat dissipating surface area of the shield.

10. A heat dissipating, electrical shield for electronic components as :defined in claim 1 in which the metallic envelope comprises a tube having a plurality of flattened, return bent, outwardly extending, annular fins formed from its wall and spaced longitudinally along the tube.

11. A heat dissipating, electrical shield for electronic components as defined in claiml in which said metallic envelope comprises a tube having a plurality of flattened, return bent, outwardly extending, annular fins formed from its wall and spaced longitudinally along the tube; said tube having a longitudinal slot in its Wall extending from its free end to a point adjacent the mounting end thereof to accommodate variations in the diameter of the component envelope.

12. A heat dissipating, electrical shield for an electronic tube having a non-metallic envelope comprising: a substantially cylindrical resilient metallic enclosure having an inside diameter slightly small that the diameter of the tube envelope on which it is to be fitted, said enclosure having a slot therein providing for expansion of the enclosure to receive the tube in intimate thermal contact with its envelope; and fins mounted at the exterior of said enclosure and extending outwardly therefrom to augment the heat dissipating surface of the shield.

13. A heat dissipating, electrical shield for electronic components comprising: a substantially continuous metallic envelope formed to closely embrace the non-metallic envelope of an electronic component in substantially continuous good heat conducting contact therewith, and forming a shield against ambient electrical fields; and heat dissipating elements attached to said metallic envelope and extending outwardly therefrom to augment the heat dissipating surface area of the shield, said metallic shield envelope being directly mounted on said non metallic component envelope by a non-metallic, heat conducting cement.

14. An electronic tube comprising: a non-metallic envelope enclosing the tube elements; a substantially con tinuous metallic shield surrounding said tube envelope; a non-metallic, heat conducting cement afiixing said shield to said envelope; and metallic fins attached to said shield and extending outwardly therefrom to augment the heat dissipating surface thereof.

15. An electronic tube comprising: a non-metallic envelope enclosing the tube elements; a substantially continuous metallic shield surrounding said tube envelope; a non-metallic, heat conducting cement afiixing said shield to said envelope; metallic fins attached to said shield and extending outwardly therefrom to augment the heat dissipating surface thereof; and means on said shield for electrically and thermally connecting it to an electronic chassis.

16. An electronic tube comprising: a non-metallic envelope enclosing the tube elements; a substantially continuous metallic shield surrounding said tube envelope; said shield being formed from discrete elements having curved portions conforming to the surface of the tube envelope; a heat conducting, plastic cement affixing said curved portions directly to said envelope surface; and fins integrally attached to said curved portions and extending outwardly from the tube envelope to augment the heat dissipating surface of the shield.

References Cited in the file of this patent UNITED STATES PATENTS 1,924,368 McCullough Aug. 29, 1933 2,011,647 Mouromtsefi' et al. Aug. 20, 1935 2,289,984 Mouromtseif et al. July 14, 1942 2,357,727 Craig Sept. 5, 1944 2,499,612 Staver Mar. 7, 1950 2,745,895 Lideen May 15, 1956 2,771,278 Slack Nov. 20, 1956 2,772,861 Dailey Dec. 4, 1956 2,862,991 Reardon Dec. 2, 1958 2,883,446 Nye Apr. 21, 1959 2,893,704 Passman July 7, 1959 2,905,742 Woods Sept. 22, 1959 Disclaimer 3,023,264.Dmzald If. Allison, Albuquerque, N. Mex. HEAT-DIssIPATING SHIELD. Patent dated Feb. 27, 1962. Disclaimer filed Aug. 20, 1963, by the assignee, Cool Fin Electronics Corpomtion. Hereby enters this disclaimer to claim 12 of said patent.

[O/ficial Gazette October 8, 1.963.] 

